Transgenic rice expressing Trichoderma spp. endochitinase gene exhibits moderate resistance to sheath blight

Rice is a staple food consumed by almost half of the world’s population. The crop is prone to a myriad of diseases, and sheath blight caused by Rhizoctonia solani poses a major risk to its cultivation, due to non-availability of resistant genes in the crop germplasm. As a consequence, most of the cultivars are susceptible to the disease incurring significant crop yield losses. This study delineates development of transgenic rice expressing Trichoderma spp. endochitinase through Agrobacterium-mediated genetic transformation. The presence of transgene in T0 plants was detected by PCR, and its transcription confirmed through RT-PCR. The transgenic plants revealed up to six-fold higher relative transgene expression as compared to non-transgenic plant through qRT-PCR. Upon bioassay with virulent R. solani isolate, T0, T1 and homozygous T2 progeny plants (possessing high level of endochitinase expression) exhibited moderately resistant reaction to the pathogen. The quantitative analysis for sheath blight incidence displayed significantly lower AUDPC values in T1 progeny plants as compared to NT plant, with former displaying up to 67.65% reduction in disease index coupled with slower disease progression. The moderate resistant reaction was verified in T2 progeny plants, thus confirming the role of endochitinase in improved resistance. These plants are a valuable source for introgression of sheath blight resistance in rice breeding programs.